As a fusion device used for an image forming apparatus such as an electrographic photocopy machine, facsimile, printer, and multi-function peripheral, a fusion device using an endless belt has been known. For example, in JP Laid-Open Patent Application No. 2010-139982, a fusion device that is provided with two endless belts (first belt and second belt) that rotate around and move maintaining an oval shape and that is configured to form a free nip part between the endless belts is disclosed.
However, in the conventional fusion device, it is sometimes difficult to form a stable nip between the first belt and the second belt.
The present invention is for solving the above-described problem, and one of the objects of the present invention is to provide a fusion device capable of forming a stable nip and an image forming apparatus provided with the fusion device.